Ds1 (10) plays trains/plays football 4 times a week, he also does athletics, judo and swimming once weekly also...
When at school he also does more football, hockey, tennis and rugby (represents the school in these sports) he absoutely loves doing all this, and because he's fit and active and eats a nutritious and healthy diet with plenty of water I've never been overly fussed, he choose and enjoys doing all these sports and gets really upset if he can't attend any of them, except the past few months I've been getting increasing anxious and not because of ds1.
My dh coaches at academy level and also our sons football club (county), all we have been hearing lately is young children and adults dropping dead! We heard of 3 children last month alone. 
Dh school friend dropped down dead also when he was ds age at Sports Day.
Today in my home town a young boy has died after 6 days in a coma after his heart stopped at football training.
AIBU to even contemplate asking the doctor to test ds heart, would he think I was some crazy mother, it has me worried sick!